The release of the group's annual inequality report coincides with the World Economic Forum in Davos. The annual meeting in the Swiss mountain resort brings together political and financial leaders and some of the wealthiest people in the world.

The Oxfam report said that the richest 1% has owned more wealth than the rest of the planet since 2015. In the U.S., the richest 1% control 42% of the wealth.

It has been four years since the WEF identified rising economic inequality as a major threat to social stability. But Oxfam said the problem is just getting worse.

"Despite world leaders signing up to a global goal to reduce inequality, the gap between the rich and the rest has widened," it said.

The report said that seven out of 10 people live in a country where inequality has worsened over the past three decades. And over the past 25 years, the top 1% has gained more income than the bottom 50% put together.

"Far from trickling down, income and wealth are being sucked upwards at an alarming rate," the report said.

There's also a big gender disparity. Of the 1,810 dollar billionaires around the world, 89% are men.